rec

[syntax] rec var exp

[syntax] rec (name . variables) body

SRFI-31: creates recursive function.

(define-syntax rec
  (syntax-rules ()
    ((rec (NAME . VARIABLES) . BODY)
     (letrec ( (NAME (lambda VARIABLES . BODY)) ) NAME))
    ((rec NAME EXPRESSION)
     (letrec ( (NAME EXPRESSION) ) NAME))))

ChezScheme: Creates a recursive object.

  (define-syntax rec
    (syntax-rules ()
      ((_ x e) (letrec ((x e)) x))))

See also letrec.

MIT-Scheme has named-lambda, which is equivalent to the second form of rec.